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The effects of viscoelastic properties of the wetting liquid on the kinetics of the disc granulation process

Obraniak, Andrzej, Orczykowska, Magdalena, Olejnik, Tomasz P.
Powder technology 2019 v.342 pp. 328-334
aqueous solutions, droplets, flour, liquids, models, potato starch, powders, raw materials, rheometers, viscoelasticity
The study investigates of rheological properties of the wetting liquid (potato starch solutions). Studies on viscoelastic properties of wetting liquids were carried out using the rotational rheometer Physica MCR 301 made by Anton Paar with the cone-plate measuring system. Rheological parameters of the medium were described using the fractional rheological Maxwell-Wiechert model.The studies on granulation kinetics were carried out in the laboratory disc granulator with diameter D = 0.5 m. The binding liquid was supplied to the pouring bed with a constant flow rate through the nozzle which generated droplets sized approx. 4–6 mm. The model raw material was the calcareous flour, whereas as the wetting liquid - water or aqueous solution of potato starch of 3% and 6% concentration was used. Droplets were given at different times - from 2 to 16 min. For particular times of the process its granulometric composition was determined along with the share of ungranulated material in the total mass of the processed bed and its mean diameter. The impact of rheological parameters of the wetting liquid on granulation kinetics was determined and a model was proposed which makes the process constant dependent on viscoelastic parameters of applied liquids.